We plan to produce series of items that need to be black or almost black and it seems that the only way would be to use commercial RIT dye powders available also in black.

Will dyeing black get rid of the light transmission properties of the WSF?
Has anyone actually dyed WSF with RIT powder?
How does it held up in the UV/Sun?
Is dyeing more durable option than paint if the item flexes a bit?

The only other option would be the black detail material but I can not risk the items to look silverish from certain angles as our intended use of printed products is optical/light ray elimination.

WSF dyes quite deeply with RIT dyes in my experience. I went by the instructions with a quarter package of purple. I submerged the WSF piece (and others) into the boiling dye bath for a minute. What I recieved from the purple dye was a black black colour. It wasn't until I used only hot water and a dip of 5 seconds that I recieved a piece that was a very dark purple. Therefore, I surmise that you will have no problem with black RIT fabric dyes.

... I submerged the WSF piece (and others) into the boiling dye bath for a minute. What I recieved from the purple dye was a black black colour. It wasn't until I used only hot water and a dip of 5 seconds that I recieved a piece that was a very dark purple. Therefore, I surmise that you will have no problem with black RIT fabric dyes.

-Whystler

Thanks for the info.
Can you remember if the darkened WSF was still a bit translucent when you accidentally dyed it black?
My model has 2mm thick walls so I hope that after dyeing it will not let any light through.

Sorry, but there is no way to tell whether it was translucent since the WSF model I died was not thin enough. However, I just did a test on the White Detail one I died just as darkly that had a thin wall and it was slightly purply translucent when I inserted an LED. Unfortunately, the two materials are so different that this information will not tell you anything about WSF.

I dyed some of my WSF puzzle pieces "scarlet" red using RIT fabric dyes. I submerged them in a boiling dye bath for about a minute. They look great!

A week later a friend played with my puzzle for 20 minutes, and after that his fingers became red with the dye! Any tips on how to keep this from happening? What about putting salt in the dye bath? Or maybe washing the parts a lot after dying?

I've perfected the dying process, and would recommend leaving WSF pieces in the boiling dye bath for at least 10 minutes up to a half-hour. I boil the dyed water, then remove it from the stove and add my pieces. It can get messy boiling the pieces in the water.

Vinyl Dye is the quickest and easiest way. You can buy it in spray cans from auto stores. Some colours work better than others as far as their penetrating qualities. It doesn't build up easily like paint does, and only runs if you are too liberal with the coats.

Though it can be tough to achieve a perfect finish. Thicker sections don't dye as readily as thinner ones. And it doesn't completely dye a part, only about 2mm deep. But it works, and no need for RIT dye.

A slightly acidic after-bath will help 'set' any organic dye, as seen in fiberarts, etc. Helps RIT as well. A first-blush trial might be, say, white vinegar @ 1 cup per gallon of water.
Then, perhaps a scotch-guard run (!) and/or some form of a light sealant.... perhaps someone has tried a silicone grout sealant (water-clear and water-like viscosity)..... ?